1. Field of the Invention
2. Description of the Prior Art
As disclosed in TW M257924 and TW 437519, a conventional hand tool can drive a screw or a nut to rotate for fastening purposes. Another hand tool as disclosed in TW M361408 provides a ratchet mechanism whose axis can be adjusted. However, the driving portion thereof has fixed dimension. Thus it requires several hand tools in order to drive workpieces with different dimensions. Accordingly, adapters are arisen to mitigate such disadvantages. Nevertheless, it still requires several adapters in order to correspond to workpieces with different dimensions.
To fit with workpieces with different dimensions, U.S. Pat. No. 6,382,054 discloses a wrench. However, the wrench meets some problems in durability and practicability. As the openings are formed larger in size, the thickness of the wrench between two adjacent openings is going smaller. As a result, the mechanical strength of the wrench is weakened. Besides, the openings penetrate from flat surfaces to the cylindrical opening. When the wrench is put on a nut, the nut will probably fall into the cylindrical opening.